The invention relates to a method for the infrared-light-induced yield optimization of chemical reactions, particularly synthesis reactions as well as the use of infrared light pulses.
From WO 2006/069448 A2 a method for removing material by means of infrared light laser pulses is known, in which the energy of the infrared light is converted into heat energy of the material to be removed. Within the material to be removed hot spots are produced here, in which the temperature lies above the vaporization point of at least one component of the material to be removed.
From WO 2007/082861 A1 a method for synthesizing product molecules is known, in which energy is introduced by laser pulses of visible light into molecules of the starting material that are to react, wherein the reaction of the starting material molecules into product molecules takes place on a surface on which the molecules of the starting material are at least partly absorbed. When introducing visible light, an electronic excitation is induced.
From DE 10 2011 050 894 A1 a method for polymerizing monomer units and/or oligomer units by infrared light pulses is known, in which particularly chirped infrared light pulses are used to allow for higher vibration excitations. Here, excitations of multiple coherent vibration quanta of a vibration mode occur simultaneously in a molecule. This method is based on multi-photon processes.
It is known, for instance from C. J. Hawker, Chem. Rev. 2001, pages 3661-3688, that by electronic excitation with wavelengths shorter than 2000 nm, particularly 1000 nm, in some organic molecules radicals are produced, which can induce chemical reactions.
Furthermore, it is known, for instance from R. Bonnett, Chemical Society Reviews, 1995, 24(1), pages 19-33, that by electronic excitation in the wavelength range shorter than approximately 1200 nm, some organic molecules, particularly of the classes of molecules of the porphyrins, pthalocyanines, corroles, chlorines, pheophorbides and the tetrapyrroles, produce reactive singlet oxygen by triplet annihilation, which said reactive singlet oxygen induces chemical reactions.
It is equally known, for instance from A. Zewail, J. Phys. Chem. A 2000, 104, pages 5660-5694; R. N. Zare, Science 1998, 279, pages 1875-1879; “Analysis and Control of Ultrafast Photoinduced Reactions”, Springer Series in Chemical Physics 87, 2007, editors: Oliver Kuhn and Ludger Wöste, that by electronic excitation with coherent light pulses which produce a quantum interference of vibration modes, chemical reactions, particularly dissociation reactions, can be controlled in the electronically excited state. This controlling of chemical reactions was also object of the Research Program 450 “Analysis and Control of light-induced chemical reactions” (SfB450).
In contrast to this, there are only few examples for chemical ladder climbing dissociation reactions by vibration excitation by means of infrared light pulses (T. Witte et al. J. Chem. Phys. (2003), 118, pages 2021-2024). Herein, the excitation of multiple coherent vibration quanta of a vibration mode in the electronic ground state occurs simultaneously in a molecule. For this, the absorption of multiple photons by the individual molecule is necessary.
D. Zeidler et al. (J. Chem. Phys. (2002), 116, pages 5231-5235) have introduced an experiment for the optimal control of the ground state dynamics. Here, a stimulated Raman process is optimized with visible light via a computer-controlled feedback loop in such a way that the coherent Raman active ground state vibrations can be manipulated in their phase. Thereby, in a time range of approximately one picosecond (ps), coherent wave packets can be produced, the relative phase of which to each other can be changed. This is only possible as long as the dephasing time lying between 0.1 ps and approximately 1.5 ps, is not over yet.
In the publication of N. C. Strandwitz et al., J. Am. Chem. Soc, 2008, 130, pages 8280-8288, a method was specified, in which the efficiency of the photo-polymerization—initiated by electronic excitation—is increased by approximately 5% due to the presence of a co-initiator. In said work, one- and two-photon absorption processes were used to electronically excite CdS semiconductor quantum dots and to produce radicals.
There have also been reports on the theoretical possibility of exciting coherent Raman active ground state vibrations by coherent excitation with light pulses in the visible spectral range, which can open a chemical reaction path.
Up to this day, no method has been specified and no research is known in which a reaction coordinate is directly or indirectly excited or activated by one-photon vibration excitation and thus a chemical reaction or chemical synthesis is deliberately controlled and/or accelerated.